Crystalline thermoplastic compositions

ABSTRACT

CRYSTALLINE POLYOLEFIN AND POLYAMIDE COMPOSITIONS NUCLEATED WITH SULFONIC ACIDS AND SALTS THEREOF OF THE FORMULA   ME-O3S-AR(-Y1)(-Y2)-(SO3-ME)M   WHEREIN AR IS NAPHTHALENE, ME IS AN EQUIVALENT OF A METAL, PREFERABLY ALKALI METAL, OR HYDROGEN, M IS 0 OR 1, Y1 IS AN AMINO GROUP IN THE 5- OR 8-POSITON, AND Y2 IS -OH OR HYDROGEN, HAVE LOWERED CRYSTALLIZATION HALFTIMES AND A MORE UNIFORM SPHERULITE STRUCTURE, WHICH RESULTS IN MORE RAPID MOLD RELEASE DURING CYCLIC OPERATING PROCEDURES, IMPROVED MECHANICAL PROPERTIES, AND IMPROVED TRANSPARENCY.

United States Patent O 3,740,380 CRYSTALLINE THERMOPLASTIC COMPOSITIONS Ursula Eichers, Recklinghausen, and Otto Hahmann,

Heinz-Hermann Meyer, Konrad Rombusch, and Manfred Rossbach, Marl, Germany, assignors to Chemische Werke Huels Aktiengesellschaft, Marl, Germany No Drawing. Filed Jan. 21, 1971, Ser. No. 108,597 Claims priority, application Germany, Jan. 22, 1970, P 20 02 650.0 Int. Cl. C08f 45 /0.0; C08g 41/00, 51/00 US. Cl. 26078 S 17 Claims ABSTRACT OF THE DISCLOSURE Crystalline polyolefin and polyamide compositions nucleated with sulfonic acids and salts thereof of the formula wherein Ar is naphthalene; Me is an equivalent of a metal, preferably alkali metal, or hydrogen; m is or 1; Y is an amino group in the 5- or 8-position; and Y is OH or hydrogen, have lowered crystallization halftimes and a more uniform spherulite structure, which results in more rapid mold release during cyclic operating procedures; improved mechanical properties; and improved transparency.

BACKGROUND OF THE INVENTION This invention relates to crystallizable and crystalline thermoplastic polyolefin and polyamide compositions, more preferably nucleated thermoplastic compositions.

It is known that certain polymers are crystallizable, i.e. form partially crystalline solid bodies during cooling of the melt. A prerequisite for the crystallization is a substantially completely regular structure of the polymer chain. Among the partially crystalline polymers are, for example, polyesters, polyvinylidene chloride, polytetrafiuoroethylenes, polyamides and polyolefins, especially polyethylenes and the higher poly-a-olefins. Copolymers are also capable of crystallization if at least one of the monomers, which is crystallizable as a homopolymer, is present in suflicient block length.

The crystalline proportion of partially crystalline polymers can vary within wide limits, but generally does not exceed 80-90%. The basic building block of the crystalline zones is the unit cell, the form and dimensions of which are dependent on the structure of the chain and on the intermolecular force. Of much greater importance to the mechanical properties is the over-all macrocrystalline structure, i.e., the manner in which the unit cells are aggregated into larger zones. For example, such zones, which often are visible as lamellae or spherulites, exhibit in polypropylene films a profound influence on the transparency and the tensile strength. It is likewise known that the tensibility of fibers and filaments depends on the structure and arrangement of the lamellar zones.

A number of measures are known which make it possible to influence this crystalline structure. Among such measures are tempering, i.e., the thermal secondary treatment of finished molded final products; the quenching of the molded article, i.e., the accelerated cooling thereof; and finally also any type of mechanical aftertreatment resulting in an orientation of the molecular chains.

However, a particularly advantageous method has proved to be an accelerated crystallization obtained by direct interference with the crystallizing process, i.e., by the addition of nucleators. This measure provides a number of advantages, inter alia:

(1) more rapid mold release during cyclic operating procedures;

(2) improved mechanical properties; and

(3) improved transparency.

It is particularly desired, especially in film, filament, and fiber field, to have nucleating agents available which exhibit a maximum effect at a minimum concentration, i.e., which, on the one hand, accomplish the desired acceleration in crystallization particularly rapidly without themselves appearing in recognizable form as additives which could impair the mechanical, optical and other properties of the polymers.

Thus, it is known from U.S. Pats. Nos. 2,991,264; 3,118,847; 3,207,735; 3,207,736; 3,207,737; 3,207,738; and 3,207,739; as well as 3,367,926; and from Appl. Pol. Sci. 11, 673 (1967) that certain additions of foreign substances, added to the polymer melt in finely divided form, can serve as nucleating agents for the subsequent crystallization of the polymers during cooling and favorably influence the crystalline structure.

Substances which exert a nucleating action on the crystallization of a-olefins include inorganic compounds, usually metallic salts, as well as organic compounds, including aromatic or aliphatic monoand polycarboxylic acids and the amino and nitro derivatives thereof and salts thereof, and also certain sulfo compounds. Such compounds are described in detail, especially in U.S. Pat. No. 3,367,926. Of such substances, unsubstituted benzenecarboxylic acid salts are among the compounds exhibiting greatest effectiveness (Example 4), whereas the amino derivatives thereof exhibit the lowest effect among the number of tested compounds.

This invention is directed to polyamides and polyolerfins containing readily available, highly effective nucleating agents.

SUMMARY OF THE INVENTION The crystallizable and crystalline thermoplastic polyolefin and polyamide compositions of this invention comprise an aromatic sulfonic acid, or salt thereof, of the formula some-(1) wherein Ar is naphthalene; Me is an equivalent of a metal, preferably alkali metal, or hydrogen; m is 0 or 1; Y is an amino group in the 5- or 8-position; and Y is OH or hydrogen.

These compounds are 5- or 8-amino-monoand -disulfonic acids and the full or half metal salts thereof, which can additionally contain a hydroxyl group, which is preferably positioned between the amino group and a sulfonic acid group.

DETAILED DISCUSSION It is surprising that the amino-substituted compounds of the compositions of this invention are highly effective nucleating agents because it appears from U.S. Pat. No. 3,367,926 that the introduction of an amino group into the aromatic system reduces effectiveness considerably. Consequently, it would be expected that the low effectiveness of aromatic sulfonic acids and the salts thereof, would be reduced even more by the introduction of an amino group. Surprisingly, the opposite is the case. Not only is effectiveness not reduced, it is significantly increased. The

additives in all cases result in the formation of a uniform spherulite structure.

Examples of polyolefins whose crystallization times are reduced by the nucleating activity of the additives as defined herein are the normally solid crystallizable polymers of oL-IIlOI'lOOlCfiHS, preferably thOse of olefins containing 2 to 8 carbon atoms, e.g., low-pressure and highpressure polyethylene, polypropylene, polybutene-(l), and polypentene-(l). Others are 4-methyl-1-pentene, and l-hexene, crystalline copolymers of propylene with ethylene, l-butene and the like, and crystalline polystyrene. Particularly desirable improvements are obtained, for example, in block polymers, such as those consisting predominantly of isotactic polypropylene having small amounts of ethylene, e.g., between 1 and 10 percent, copolymerized therewith by block polymerization, isotactic polymers of u-monoolefins having at least 3 and up to 8 carbon atoms per molecule, and polymers of a-monoolefins having from 2 to 4 carbon atoms.

Examples of normally solid crystallizable polyamides are the known moldable, extrudable, film forming, fiber forming and/or filament forming nylons, e.g. nylon 12, nylon 66, nylon 11, and nylon 6.

It will be apparent that the particular structure of the nylon or polyolefin is not critical as long as it is normally solid and crystallizable from a melt with a crystallization half-time which is long enough so as to be improved by nucleation.

In the above formula Me can be, for example, Ca, Mg, Zn, Cu, Li, or preferably Na or K.

Examples of compounds of this invention are the sodium salt of S-amino-l-naphthalenesulfonic acid; S-amino-l-naphthalenesulfonic acid; S-amino-l-naphthalenesulfonic acid; 5-amino-3-hydroxy-l-naphthalenesulfonic acid; S-amino-1,3-naphthalenedisulfonic acid.

The nucleating additives of this invention are usually employed in concentrations of 0.0052%, preferably 0.05- 1% by weight, most preferably about 0.5% by Weight, based on the polyolefin or polyamide. However, favorable effects can also result employing concentrations above or below these limits.

Although the additives can be incorporated into the polyolefin or polyamide during the polymerization or polycondensation, generally it is advantageous and preferred to add the high-melting additives of the present invention, most preferably in an extremely finely divided form, to the polyamide or polyolefin prior to the processing thereof, e.g., prior to granulation. The additives can also be incorporated by other processing methods known in the art, for example in the melt, to the granulated or powdered polymer or in the heat-plasticized state by thermal plasticizing on masticating rolls.

Quantitative measurements of the degree of crystallinity of partial crystalline polymers can be conducted, inter alia, with the aid of X-ray diifraction or differential thermoanalysis. Examinations of the spherulite structure can be conducted by light microscope or electron microscope. In case of oriented crystallite structures (for example, in case of elongated fibers or films), an examination of the texture by X-ray analysis is suitable.

Rates of crystallization can be measured either isothermically or under temperature-programmed cooling, by differential thermoanalysis or dilatometry.

Along with an accelerated crystallization rate, more uniform spherulite structures can be observed under the light microscope with polymers containing an additive of this invention. In this connection, it is especially surprising that due to the action of the nucleating agent, the spherulites become markedly smaller, i.e., formation of coarse crystal structures is strongly suppressed or completely avoided.

The improvement in the properties of partially crystalline synthetic polymers produced in accordance with the process of the invention include increased transparency, as well as improved tensile properties of fibers and films. This improved tensile behavior permits a substantially increased take-up rate in the stretching (orientation) step, which can be increased, for example, by three to five times, compared to the same polymer lacking a nucleating agent. This results in a considerable increase in output, which is a very important factor for the processor.

For the production of films, bands, flat filaments, film fibers, tubes, or similar shapes, a crystalline linear polyolefin or polyolefin copolymer provided with the abovementioned crystallization nucleators is plasticized in an extruder and extruded, e.g., through a ring or fishtail die. During this process, a bubble is drawn out of the die, usually in the upward direction in a vertical orientation. The extrusion can, of course, be conducted from the top toward the bottom or in a horizontal direction. Alternatively, the amorphous mass is sprayed onto rolls or into a water bath and withdrawn as a fiat film.

The thus-produced blown or fiat films, or the sheets cut into strips of any desired width are either immediately conducted into an orientation unit or reeled-up onto a roll and thereafter oriented by stretching in a separate process, usually in a monoaxial manner. The polymer can be heated in a gaseous medium, usually air, or in a liquid medium, or by means of heated stretching rollers. Conducting the stretching process by means of heated rollers has the advantage that a transverse stretching takes place simultaneously with the monoaxial orientation, thus contributing significantly to transverse strength, if such property is desired. The crystalline flat articles are stretched by a multiple of their initial length in the thermoelastic range. With the same degree of stretching, the stretching rate of the films or bands can be increased, by the preceding controlled crystallization process, by a multiple of the original value, so that higher wind-up or reeling speeds and thus higher production efficiencies result.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

EXAMPLE 1 A low-pressure polyethylene copolymer with 2% of polybutene-( 1) is extruded on a blown-film extrusion machine of a conventional construction vertically from the bottom toward the top into a tube with a blow-up ratio of 1:1.2 and a take-oil speed of 15 m./min., and then laid flat and wound up. The thickness of the film is 60,41.- The doubled, laid-flat film is later cut into strips of a width of 10 mm. while being taken off the roll and conducted into a stretching unit consisting essentially of two stretching roll (godet) racks and a hot-air duct. With a stretching ratio of 1:7 and an air temperature of -1l0 C., stretching rates of 60-80 m./min. can be achieved, considering a uniform reduction of the width and thickness of the bands which are essentially proportional to the square root of the stretching ratio. With higher stretching rates, rupturing and variations in the dimensions of the band are incurred. The variations in dimension, which are manifested in the manner of an irregular wavy line along the stretched film bands, can be slightly reduced by increasing the stretching ratio, which, however, can only be attained at the expense of possible production stoppage.

Another portion of the same polyethylene is intimately admixed with 0.5% by weight of the sodium salt of 8- amino-l-naphthalenesulfonic acid or 5-amino-4-hydroxy- 1,3-naphthalenedisulfonic acid, and the polyethylene-additive mixture is extruded into blown films in the same manner. During the stretching step, production rates of more than 200 m./min. are achieved without the occurrence of the above-mentioned dimensional variations and ruptures.

A low-pressure polyethylene homopolymer exhibits a similar behavior when provided with the same additives. Comparable results are likewise obtained with polypropylene and polybutene-(l), as Well as with nylon 6, 66, 11 and 12.

EXAMPLES 2-39' The table below contains the data obtained with a 'variety of sulfonic acids and the salts thereof evaluated for their crystallization-accelerating eifect in a dilatometric experiment. The nucleating additives were added in proportions of 0.0052% by weight, inter alia, to a commercially available Ziegler polyethylene in a high-speed mixer, and the powdery mixtures were then homogenized on a hot roll for about 1 minute at 186 C. After melting at 185 C., the isothermic decrease in volume was observed at 126 C. during about a 24 hour period. With other types of polyolefins, and in case of polyamides, different temperatures are required. The half-times listed in the table are the periods after which one-half of the crystallizable material is present in the crystalline form.

6 wherein Ar is naphthalene and -(l) signifies a l-position substituent; Me is an equivalent of a metal selected from the group consisting of Ca, Mg, Zn, Cu, Li, Na and K or hydrogen; in is 0 or 1; Y is amino in the 5- or 8-position; and Y is OH or hydrogen.

2. A composition according to claim 1, wherein Me is Na, K or H.

3. A thermoplastic polyolefin composition according to claim 2, wherein the polyolefin is a polyethylene.

4. A thermoplastic polyolefin composition according to claim 3, wherein th polyethylene is low-pressure polyethylene-2% polybutene-l copolymer.

5. A thermoplastic composition according to claim 1, wherein the additive is selected from the group consisting of S-amino-l-naphthalenesulfonic acid, 8-amino-1-naphthalenesulfonic acid, the sodium salt of 8-amino-1-naphthalenesulfonic acid, and 5-amino-8-hydroxy-l-naphthalenesulfonic acid.

6. A thermoplastic composition according to claim 1, wherein the additive is S-amino-l-naphthalenesulfonic acid.

7. A thermoplastic composition according to claim 1, wherein the additive is 8-amino-l-naphthalenesulfonic acid.

TABLE Half-time of Measuring crystallizatemperature tion (min.) C.)

1. LP-polyethylene (M.W. about 50,000, softening point 118 0., density 0.95 g./cm. 180 126 2. +05% by wt. 5-amino-1-naphthalenesulfonic acid 76 126 3. +05% by wt. 8-amino-1-naphthalenesulfonic acid 126 4. +05% by wt. 8-amino-1-naphthalenesulionic acid, sodium salt. 56 126 5. +0.005% by wt. 8-amino-l-naphthalenesulfonic acid, sodium salt. 165 126 6. +0.05% by wt. 8-amino-1-naphthalenesulionic acid, sodium salt. 91 126 7. +10% by wt. S-amino-l-naphthalcnesulfonic acid, sodium salt. 51 126 8. +20% by wt. S-amino l-naphthalenesulfonic acid, sodium salt 60 126 90. +05% by wt. 5-amino-4-hydroxy-1,3-naphthalenedisulfonic acid 126 11. +05% by wt. 8-amin0-5-hydroxy-l-naphthalenesulionic acid 111 126 12. +05% by wt. 5-amino-8-l1ydroxy-l-naphthalencsulfonic acid 98 126 13. +0.5% by wt. 8-amino-4-hydroxy-l,7-naphthalenedisulionic acid 117 126 14. +05% by wt. 8 amino-4-hydr0xy-1,7-naphthalenedisulionic acid, dipotassium salt-.." 129 126 15. +05% by wt. B-amino-l,7-naphthalenedisu1fonic acid 131 126 16. +05% by wt. 8-amin0-1,3-naphthalenedisulfonic acid, monosodium salt 101 126 17. +05% by wt. B-amino-2-hydroxy-1-naphthalenesulionic acid 112 126 18. +0.5% by wt. 8-arnino-2-hydroxyJ-naphthalenesulfonic acid, magnesium salt 129 126 For comparison 19. +05% by wt. 2-hydroxy-1-naphthalenecarboxylic acid 126 20. +0.5% by wt. 5-amin0-1-naphthalenecarboxylic acid 165 126 21. +05% by Wt. 4-amino-1-nitr0naphtl1alene 165 126 22. +05% by wt. 4-amino-3-hydroxy-1-naphthalenecarbo 150 126 23. +05% by wt. 7-amino-1-naphthalenesulfonic acid- 165 126 24. +05% by wt. l-naphthalenesulfonic acid.. 126 25. +05% by wt. 2-naphthalenesulfonic acid.- 126 26. +05% by wt. 4-amino-5-hydroxy-l-naphthalenesulfonic acid. 160 126 27. +05% by wt. 5-amino-2-naphthalenccarboxylic acid u 160 126 28. +05% by wt. 2-amino-5-hydroxy-1,7-naphthalenedisulionic acid, monosodium salt. 160 126 29. +0.5% by Wt. 6-amino-2-naphthalenesulfonic acid 165 126 30. Polypropylene (M.W. about 300,000, softening point 146 O.) 2, 000 145 31. +05% by wt. 8-amino-4hydroxy-1-naphthalenesulfonic acid- 465 145 32. +05% by wt. 5-a1nino-1-naphthalenesulfonic acid 479 145 33. +05% by wt. 5-amino-4-hydroxy-1,3-naphthalenedisulfonic acid, disodium salt.- 520 145 34. Polybutene-l (M.W. about 1 500,000, softening point 123 C.) 200 104 35. +05% by wt. 5-amino-4-hydroxy-1-naphthalenesulfonic acid 119 104 36. +05% by wt. S-amino-naphthalenesnlfonic acid, potassium salt 135 104 37. Polyamide 12 41 168 38. +05% by wt. 8-amino-fi-hydroxy-l-naphthalenesulfonic acid 22 168 39. +05% by wt. 5-amino-naphthalenesulfonic acid, calcium salt 31 168 The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to ada t it to various usages and conditions.

What is claimed is:

1. Crystallizable thermoplastic polyolefin or carbonamide chain linked polyamide composition containing a nucleating elfective amount of an additive of the formula 8. A thermoplastic composition according to claim 1, wherein the additive is the sodium salt of 8-amino-1-naphthalenesulfonic acid.

9. A thermoplastic composition according to claim 1, containing 0.005-2% by weight of the additive.

10. A thermoplastic composition according to claim 9, containing ODS-1.0% by weight of the additive.

11. A thermoplastic composition according to claim 10, containing about 0.5% by weight of the additive.

12. A thermoplastic composition according to claim 1, wherein the additive is 5-amino-4-hydroxy-1,3-naphthalenedisulfonic acid.

13. A thermoplastic polyolefin composition according to claim 2 wherein the olefin is a polypropylene and the additive is 8-amino-4-hydroxy-l-naphthalenesulfonic acid.

14. A thermoplastic polyolefin composition according to claim 2 wherein the olefin is a polypropylene and the additive is a disodium salt of 5-amino-4-hydroxy-1,3- naphthalenedisulfonic acid.

7 8 15. A thermoplastic polyolefin composition according References Cited to claim 2 wherein the olefin is a polybutene-l and the UNITED STATES PATENTS additive is 5-amino-4-hydroxy-3-naphthalenesulfonic acid. I

16. A thermoplastic polyolefin composition according 3,327,021 6/1967 'Bmsbergen ZGOQDIG 35 to claim 2 wherein the olefin is a polybutene-l and the 5 additive is a potassium salt of 8-amino-naphthalenesul- JAMES SEIDLECK Pmnary Exammer fonic acid. A. HOLLER, Assistant Examiner 17. A thermoplastic polyamide composition according to claim 2 wherein the polyamide is nylon 12 and the additive is a calcium salt of S-amino-naphthalenesulfonic 10 2 S 935 A acid. 

